The research is concerned with variables which influence the discrimination among memories. Two lines of experimentation are being followed. In one the critical questions evolve around factors which influence the discrimination between lists of words which have been presented for learning. Included also in this approach is work on a phenomenon that is believed to result from differences in list discrimination. This phenomenon is found if two or more lists are learned simultaneously; the long-term recall of lists learned simultaneously is better than the recall of lists learned in isolation. The major experiment being conducted is to see if proactive interference producted by classical interference paradigms is reduced if simultaneous learning is involved. The second line of research asks about interference within a list when interference paradigms are involved. In a completed experiment, the strength (number of study trials) of the completing items was varied. Severe interference effects were obtained but the magnitude of the interference was unrelated to the strength of the items. Work continues on this problem.